Quenched spark-gap.



R. PFUND. QUENC HED smx G AP. APPLICATION f l LED DEC. 30.' l9l3.

Patented Nov. 23; 1915.

Fig.4

r m I Witnesses A ttomeys.

UNITED STATES PATEN OFFICE". ,v

RICHARD PFUND, OF NEW YORK, N. Y.

QUENCHED SPARK-GAP.

gaps used in the transmission of electromagnetic -wave energy, and hasfor its object the elimination of the thin and on that account flimsy,easily damaged and expensive insulating and more or less heat resistingspacing washers or gaskets made necessary by the various forms ofquenched spark-gaps heretofore used and the replacing of such flimsyinsulating spacing washers or gaskets by spacing washers or gaskets ofmetal. The length of each gap of a quenched sparkgap is in theneighborhood of 0.01 of an inch and with the forms of gap. heretoforeused the insulating spacing washers or gaskets must have a uniformthickness equal to this length and must be capable of withstanding adifference of po.- tential of at least 1,000 "olts and furthermore mustnot vary in thickness to any appreciable extent when subjected-to thedegree of compression employed when the gaps are set up for use. It isobvious that such thin and uniform insulating spacing washers or gasketsof, for instance, mica, rubber, paper or other similar material as havebeen used for that purpose, are not only difficult to make, but are veryfragile and easily damaged in handling and by the heat of the gap, whileon the other hand, metal spacing washers or gaskets of equal'thicknessare not only easily obtained'of the uniform thickness required, but willalso stand considerable rough handling and are not af fected by the heatof the gap and are, there fore, very much cheaper and very much moredurable than any other material. \Vith metal spacing washers it is alsopossible, on account of their not being affected bythe degree ofcompression employed, to obtain gaps of absolutely constant, uniform andequal length which is of great importance in producing perfect Signals.

In the accompanying drawings: Figure 1 is a side elevation and partialsection of a complete quenched spark-gap of eight separate unitsembodying my invention. Fig.

Specification of Letters Patent Patented Nov. 23 1915 Application filedDecember 30, 1913. Serial No. 809,436.

2 is a transverse section 0n,line 2.-2 of Fig. 1; and Fig. 3 is a sideelevation ofthe two halves of one of the spark-gap units with the partsseparated.- I

As shown in Fig. 1, the complete quenched spark-gap consists of a seriesofseparate removable units or gaps, each made oftwo halves and each halfconsisting of a metal base plate 4, insulating ring 5 and metal ring 6on top of the insulating ring. Between the two halves of the gap is themetal spacing washer or gasket? clamped between the metal'rings 6 of theadjoining halves of the gap. Between the different individual completeunits or spark-gaps, as shown in Fig. 1, are cooling plates 8 forabsorbing and radiating the heat produced by the spark,

and these cooling plates, together with the spark-gap units, aresupported in a-metal frame. The metal frame consists of invertedT-shaped end pieces 9, held together by metal rods. 10 and nuts 1 1,'themetal rods being covered with insulation 12, which may be of glass,porcelain, fiber, rubberor similar material, or a combination of suchmaterials. As shown, the cooling plates and the spark-gap units aresupported on the metal rods 10, and are insulated from these rods by theinsulation 12 and from the metal tion 13on the inner faces of the metalspacing plates 14. The terminals 15,.at-tached to ends of the frame bytheadditional' insulathe two outside cooling plates 8, are forconmeeting the complete quenched sparkvgap in circuit. A screw 16passing through one end of the supporting frame coni resses thespark-gap units, the spacing was ers or gaskets 7 and the cooling plates8 in jorder to make all the gaps of uniform length, 12.,

equal in length to the thickness of the spacing washers or gaskets7,"andto insure ,perfeet contact.between the differentunit s, theadjacent cooling plates and the terminals.

The supporting'frame is mounted upon in sulators 17, by means of whichit is insulated from the ground and other parts of the circuit. It will,of course, beunderstood that the particular form of frame and the exactarrangements described and illustrated for supporting and compressingthe individual units and'the cooling plates and other parts are notessential to the operation of theapparatus, but merely indicate aconvenient way in which the apparatus may be an ranged Theconstructionof the individualspark-gap units, however, which makes itpossible to engagemetal spacing washers or gaskets between the twohalves of eachgap in place of spac ng washers or gaskets of in sulatingmaterial heretofore used, constitutes my present invention. Thisconstruc tionis made clear from the-drawings; The

its high heat conductivity, The-insulating ring is attached means ofscrews, studs, cement or in any other approved manneiyand the insulatingto the base plate 4 by material. employed for the'rings 5 may be fiber,or like material, or glass orporcelain,

applied by screw or gasket 7 is made uniformity,

' or of tungsten or have found that ring 6, attached ing ring 5, may

to the face of each insulat be of brass-or copper and attached to thering 5 in a manner similar to; the attachment of that ring to the ,baseplate, with-the precaution,

metal screws or studs amused-,Suchscrews or studs should make noconhectionbetween'. the metal base plate land the metal ring 6,

be far enough apart not to" and that they impair the insulation betweenthe base plate and the ring 6 below that'required to safely withstandnot less than ence of potential one-half the differ- 0.01 of an inchthick, and this gasket is clamped "between the metal rings 6 'of the twohalves of' the coinplete unit when-the units are set up in the 16.The'spacing washer of substantially the same inside and outside diameteras the ring 6. I ordinaryGerman silver is readily obtainable in themarket 'of the required uniform thickness to form the spac 'ing washers7, and the purpose very any, other metal, if of sufficient strength andwould also serve. The active surfaces 18 of each gap .are made ofsilver, ;or. metal of similar high' heat conductivity,

insure their making as perfect and uniform contact as possiblewith-thebase plates. 7 The active surface 18 and the surface 19 of themetal ring 6 of each half of thespa'rk-gap unit are turned 'ofi' to beexact alinement,

. metallic spacing washer or gasket 7 placed;

and-if this is done, it isseen that when the between the two halves ofeach complete unit, as shown in ,F ig. 1, and the two halves are pressedtogether, the space between the active surfaces 18 will be equal to thethick ness of the spacing washer or gasket 7, and if the unit has beenproperly constructed,

'of its very superior .when oxidized or blackened, heat radiating,

however, that if r p thecleaning at each gap. The spacing -washer orgasket? is of metal approximately frame and pressure that it appears toanswer well, although of course similar metals having a low A plat e,and with vapor pressure and these active surfaces are and the spacingwashers or gaskets? are of the required and easily obtained uniformthickness and of sufiicient hardness so as notto be'easily pressed cratepressure employed, the active surfaces 18 will be exactly parallel toeach other. A slight depression in the center of each active surface 18,as shown in the drawing, has been found to ,be desirable, be provided."Although brass is frequently used forthe-c'ooling plates 8, I have itadvantageous to employ copper on account heat conducting and properties.There is, therefore, greater efliciency in keeping the gaps .cool andimprov- Ling thequenching action. 1 or material of similar character.The metal;

out of shape by the mod- I and should also i found I do not wish toliinit myselfto the exact shape and;dimensions or the exact constructionshown,-but merely use them to illus-' trate the principle of myinvention. For insta nce the metal ring 6 on top of the insulating-ring5 It is, however, a desirable feature in order toprovide two metalsurfaces, 2'. 6., the active surface 18 and the surfaceef thering 6, sothat when it becomesnecessary to clean or 'I'e-polish the active surface18,,thiscan be done by rubbing the face of the unit on surface (such ascrocus cloth), the twosurfaces 6 and 18 hearing on the cleaning surfaceand being; rubbed down togetherand to vthe same'extent. Thealinement'between-the active surface 18 and the surface of"the ring 6will thus be main- .tained, and this is important in order to insure thelengthof the. gap being equal to the thickness of the spacing washer ,orgasket and of uniform length over its entire surface.

Iclaim: p 1. A portion of a quenched spark gap unit, having a metal baseplate,

rounding theactive. surface, and lying wholly within the periphery ofthe 'base the plane of the active sur ace extendingtq at least theplane, of the ring of insulating material.

2. A portion of a quenched spark gap un t, having a metal base plate,active surface-on one side of the same, and a'ring of insulatingmaterial in contactwith the same side of said base plateand sur is notabsolutely essential.

with a projecting active surface on one side Ofthesame, and.

with a pr c m I rounding the active surface 'andoutof coi tactwiththesam'e, and lying wholly within the periphery'of' the base plate, andw th theplane of the active surface extending to at least the plane "ofthering-of insulati ig material.

having a metal base plate, with apr01ect- 4 3. A portion of a queiichedspark gap unit",

and a -ring, of insulating material in coiltact with the same side ofsaid base plate and secured thereto, and surrounding the .least theplane of the ring of insulating maface extending to at least the terial.

-t. A portion of a quenched spark gap unit, having a metal base plate,with a projecting active surface on one side of the same, and

a ring of insulating material'in contact with the same side of said baseplate and secured thereto, and surrounding the active surface. and outof contact with the same, and lying wholly within the periphery of thebase plate, and with the plane of the active surplane of the ring ofinsulating material.

5. A portion of a. quen bed spark-gap unit, having a metal base plate,-with a projecting active surface on One side of the same, and. a ring ofinsulating material in contact with the same side of said base plate andsurrounding the active surface. said base plate serving as the supportfor the said insulating material, and with the plane of the activesurface extending to at least the plane of the ring of insulatingmaterial.

6. A-portion of a quenched sparl -g21p unit, having a metal base plate,with a projecting active surface on one side of the same, and a ring ofinsulating material in contact with the same side of said base plate andsurrounding theactive surface and out of contact with the same, saidbase plate serving as the support forthe said insulating ma--' terial,and with the plane of the active surface extending to at least the planeof the ring of insulating material.

7. A portion of a quenched spark-gap unit, having a metal base plate,with a projecting active'surface on-one side of the same, and a ring ofinsulating material in contact with the same side of saidbase plate andsecured thereto, and surrounding the active surface, said base plateserving as the supportfor the said insulating material, and with theplane of the active surface extending to at least the plane of the ringof insulating material.

8. A portion of a quenched spark-gap unit,

having a metal base plate, with a projecting active surface on one sideof the same, and a ring of insulating material in contact with. the sameside of saidbase plate and secured thereto and surrounding the activesurface, and out of contact with the same, said base plate serving asthe support for the said insulating material, and with the plane of theactive surface extending to at least the plane of the ring of insulatingmaterial. V

A portion ofa quenched spark-gap unit, metal base plate, with a pre-5."?-

tion on one side having an active surface, and a ring of insulatingmaterial in contact with the samexgide only of said base plate, andsurrounding the active surface, and with the plane of the active surfaceextending to at least the plane of the ring of insulating material.

10. A portion of a quenched spark-gap unit, having a metal base plate,with a pro jection on one side having an active surface, and a ring ofinsulating material in contact with the same side only of said baseplate, and surrounding the active surface and out of contact with saidprojection. and with the plane of the active surface extending to atleast the plane of the ring of insulating material.

11. A portion of a quenched'spark-gap unit, having a metal base plate,with a projection on one side having an active surface, and a ring ofinsulating material in contact with the same side only of said baseplate, and secured thereto. and surrounding the. active surface, andwith the plane of the active surface extending to at least the plane ofthe ring of insulating material.

12. A portion of a quenched spark-gap unit. having a metal base plate,with a projection on one sideha-ving an active surface,

and a ring of insulating material in contact r i with tne same side onlyof said base plate and secured. thereto, and surrounding the activesurface, and out of contact with the said projection, and with the planeof the active surface extending to at least the plane of the ring ofinsulating material.

13. A portion of a quenched xpark gap unit, having a metal base plate.ith a projecting active surface on one side of said plate, a ring ofinsulating material in con 'tact with the same side of said base plateand surrounding the active surface, andlying wholly within the peripheryof the base plate, and a metal ring on the side of the insulating ringopposite from the base plate, and out of contact with the activesurface.

14. A portion of a quenched spark gap unit, having a metal base plate,with a projecting active surface on one side of said plate, a ring ofinsulating material in contact with the same side of said base plate andsurroundingthe active surface, and out of contact with the same, andlying wholly within the periphery of the base plate, and

a metal ring. on the side of the insulating ring opposite from the baseplate and out of contact with the active surface.

15. A portion of a quenched spark gap unit, having a metal base plate,with a projecting active surface ,on' one side of said plate, a ring ofinsulating material in contact with the same side of said base plateand. secured thereto, and surrounding the active surface. and lyingwholly within the ring on the side of the insulating ring opposite fromthe base plate, and out of contact with the active surface.

.716. A'portion of a quenched spark gap unit, having a metal base plate,with a prounit, havin'ga metal base plate, with a projecting activesurface on one side of said plate, a ring of insulating material incontact with the same side of said base plate and surrounding the activesurface, said base plate serving as the support for the said insulatingmaterial, and a metal ring on the side of the insulating ring oppositefrom the base plate, and out of contact with the active surface.

18. A portion of a quenched spark-gap unit, having a metal base plate,with a projecting active surface on one side of said plate, a ring ofinsulating material in contact with the same side of said base plate andsurrounding the active surface, and out of contact with the same, saidbase plate serving as the support for the said insulatingmaterial, and ametal ring on the side of the insulating ring opposite from the baseplate and out ofcontact with the active surface.

19. A portion ofa quenched spark-gap unit, having a metal base plate,with a projecting active surface on one side of said plate, a ring-ofinsulating material in contactwith the same side of said'base plate andsecured thereto, and surrounding the active surface, said base plateserving as the support for the said insulating material; and a metalring onihe side of the insulating ring opposite from the base plate,and' out ofcontact with the active surface. 20. A portion of a quenchedspark-gap unit, having a metal base plate, with a projecting. activesurface on one side of said plate, a ring of insulating material incontact with the same side of said base plate and secured thereto, andsurrounding the active surface, and out of contact with the same, saidbase plate serving as the support for the said insulating material, anda. metal ring on the side of the insulating ring opposite ,fromthe baseplate, and out of contact with the active surface.

21. A portion of a quenched spark-gap unit, having a metal base plate,with a projecti on on one side having an active surface, and a ring ofinsulating material in contact with the same side only of said baseplate, and surrounding the active surface, and a metal ring on the sideof the insulating ring opposite from the base plate, and out of contactwith the active surface.

22. A portion of a quenched spark-gap unit, having a metal base plate,with a projection on one side havinganactive surface, and a ring ofinsulating material in contact with they same side only of said baseplate, and surrounding the active surface, and out of contact withthe'same, and a metal ring on the side of the insulating ring oppositefrom the base plate, and out of contact with the active surface.

23. A portion of a. quenched spark-gap unit, having a metal base plate,with a projection on one side having an active surface,

and a ring of insulating material in contact with the same side only ofsaid base plate and secured thereto, and surroundingthe active surface,and a metal ring on the side of the insulating ring opposite from thebase plate, and out of contact with the active surface.

'24:. A portion of a quenched spark-gap unit, having a metal base plate.with a projection on oneside having an active surface, and a ring ofinsulating material in contact with the same side onlv of said baseplate and secured thereto, and surrounding the active surface, and outof contact with the same, and a metal ring'on the side of the insulatingring opposite from the base plate, and out of contact with the activesurface.

- 25. A quenched spark gap unit, composed of two similar halves, eachhaving a metal base plate, with a projecting active surface on one sideof said plate, a ring of insulating material in contact with the sameside of said plate and surrounding the active surface. and lying whollywithin the periphery of the base plate. in combination with a metalspacing washer or gaskct compressed between such two halves.

26. A quenched spark gap unit, (-(rnposcd of two similar halves. eachhaving a metal baseplate. with a projecting active surface. on one sideof said plate. a ring of insulating material in contact with the sameside of said plate. and surromnling the active surface. and out ofcontactwith thc same. and lying whollv within the periphery of thehaseplate. in combination with a metal spacing washer orgaskctcompressed between such two halves.

27. A quenched spark gap unit. composed of two similar halves. eachhaving a metal base plate. with a projecting active surface on one sideof said plate. a ring of insulating material in contact with the samesidc of said plate and secured thereto. and surrounding the active :rfac. and lvin;

lit)

of, said plat/sand secured thereto, and surrounding the active surface,and out of contact with the same, and lying Wholly within the peripheryof the base plate, in combination with a metal spacing washer or gasketcgmpressed between such two halves.

29. A quenched spark-gap unit, composed of two similar halves, eachhaving a metal base plate, with a projecting active surface on one sideof the same, and a ring of insulating material in contact with the sameside'of said base plate and surrounding the active surface, said baseplate serving as the support for the said insulating material, and withthe plane of the active surface extending to at least the plane of thering of in-' sulating material, in combination with a metal spacingWasher or gasket compressed lgetween such two halves.

- 30. A quenched spark-gap unit, composed of two similar halves, eachhaving a metal base plate, with a projecting active surface on one sideof the same, and a ring of insulating material in contact with the sameside of said base plate, and surrounding the active surface, and out ofcontact with the same said base plate serving as the support for thesaid insulating material, and with the plane of the active surfaceextending to at least the plane of the ring of insulating material, incombination with a metal spacing washer or gasket compressed betweensuch two halves.

31. A quenched spark-gap unit, composed of two similar halves, eachhaving a metal base'plate, with a projecting active surface on one sideof the same, and a 'ring of insulating materialin contact with the sameside of said base plate, and secured thereto, and surrounding the activesurface, said base plate serving as the support for the said insulatingmaterial, and with the plane of the active surface extending to at leastthe plane of the ring of insulating matrial, in combination with a metalspacing washer or gasket-compressed between such two halves.

32. A quenched spark-gap unit, composed of two similar halves, eachhaving a. metal base plate. with a projecting active surface on onesideof the same. and a ring of insula'tling material in contactwith the sameside of said base plate and secured thereto, and surrounding the activesurface, andout of contact with the same. said base plate serving as thesupport for the said insulating material. andwith the plane of theactive surface extending to at least one plane of the ring of insulatingmaterial, in com'-' insulating material in contact with the same sideonly of said base plate, and surrounding the active surface, and withthe plane of the active surface extending to at least the plane of thering of insulating material, in combination with a metal spacing washeror gasket compressed between such two halves.

34. A quenched spark-gap unit, composed of two similar halves, eachhaving a metal base plate, with a projection on one side having anactive surface, and a ring of insulating material in contact with thesame side only of said base plate, and surrounding the active surfaceand out of contact with the same, and with. the plane of the activesurface extending to at least the plane of the ring of insulatingmaterial, in combination with a metal spacing washer or gasketcompressed between such two halves.

35. A quenched spark-gap unit, composed of two similar halves, eachhaving a metal base plate, with a projection on one side having anactive surface, and a ring of insulating material in contact with thesame side only of said base plate, and secured thereto, and surroundingthe active surface, and with the plane of the active surface extendingto at least the plane of the ring of insulating material, in combinationwith a metal spacing washer or gasket compressed between such twohalves.

36. A quenched sparlcgap unit, composed of two similar halves, eachhaving a metal base plate, with a projection on one side having anactive surface, and a ring of insulating material in contact with. thesame side only of said base plate, and secured thereto, and surroundingthe active surface,

and out of contact with the same, and with a I the plane of the activesurface extending to at least the plane of the ring of insulatingmaterial. in combination with a metal spacing washer or gasketcompressed between such two halves.

37. A quenched spark gap unit. composed 38. A quenched spark'gap unit,composed i of two similar halves, each havinga metal base plate, withaq-pro ectin'g active surface on one side of said plate, a ring ofinsulating material in contact with the sameside of said plate andsurrounding the act ve surface, and out of contact with the same, and

aiimetal ring on the side of the insulating -ring opposite from the baseplate, and out of two similar halves, each having a metal" base platewith a-projecting active surface on one side of said plate, a ring ofinsulating material in contact with the same side of said plate andsecured thereto, and sur- 'rounding the active surface, and a metal ringopposite from the base plate, and out of contact with the activesurface, in combination with a metal spacing washer or gasket compressedbetween such two halves.

, 40. A quenched spark gap unit, composed of two similar halves, eachhaving a metal base plate with a projecting active surface on one'sideof said plate, a ring of insulat-' ing material in contact with the sameside of said base plate and secured thereto, and surrounding theactive'surface and out of contact with the same, and a metal ringopposite from the base plate, and out of contact with the activesurface, in combination with a metal spacing washer or gasket compressedbetween such two halves.

41. A quenched spark gap, composed of a plurality of units, eachcomposed of two "similar halves, each of which has a metal base plate,with a projecting active surface on one side of the same, a ring ofinsulating material in contact with the same side of said plate andsurrounding the active surface, and lying wholly within the periphery ofthe base plate, and a metal spacing washer or gasket compressed betweensuch halves, in combination with a metal cooling plate associated withthe base plates of contigu- "ous units onthe sides thereof opposite fromthe active surfaces;

42. A quenched spark gap, composed of a plurality of units, eachcomposed of two similar halves, each of which has a metal base plate,with a projecting active surface on one side of the same, a ring ofinsulating material in contact with the same side of said plate, andsurrounding the active surface, and out of contact therewith, and lyingwholly within the periphery of the base plate, and a metal spacingwasher or gasket compressed between such halves, 1n combination with ametal cooling plate associated with the base plates of contiguous unitson the sides thereof opposite from the active surfaces.

A quenched spark gap, composed of a plurality of units, each composed oftwo plurality similar halves, each of Which has a metal similar halves,each of whicl has a metal base plate, with a projecting activ e surfaceon one side of the same, a'i'ingfof insulating material in contact withthe same side of said plate and secured thereto, and surrounding theactive surface, ambdying wholly within the periphery of the base plate,and a metal spacing washer or gasket compressed between such halves, incombination'with a metal cooling plate associated with the base platesof contiguous units on the sides thereof opposite from the activesurfaces.

44. A quenched spark gap, composed of a plurality of units, eachcomposed of two similar halves, each of which has a metal base plate,with a projecting active surface on one side of the same, a ring ofinsulating material in contact with the same side of said plate andsecured thereto, and surrounding the active surface and out of contactwith the same, and lying wholly within the periphery of the base plate,and a metal spacing washer or gasket compressed between such halves, incombination with a metal cooling plate associated with the base platesof contiguous units on the sides thereof opposite from the activesurfaces.

45. A quenched spark-gap, composed of-a plurality of units, eachcomposed of two similar halves, each of which has a metal base plate,with a projecting active surface on one side of the same, a ring ofinsulating material in contact with the same side of said plate andsurrounding the active surface, said base plate serving as the supportfor the said insulating material, and a metal spacing washer or gasketcompressed between such halves, in combination with a metal coolingplate associated with the base plates of contiguous units on the sidesthereof opposite from the active surfaces.

46. A quenched spark-gap, composed of a plurality of units, eachcomposed of two similar halves, each of which has a metal base plate,with a projecting active surface on one side of the same, a ring ofinsulating material in contact with the same side of said plate, andsurrounding the active surface, and out of contact therewith, said baseplate serving as the support for the said insulating material, and ametal spacing washer or gasket compressed between such halves, incombination with a metal cooling plate associated with the "base platesof contiguous unitson the sides thereof opposite from the activesurfaces.

47. A quenched spark-gap, composed of a of units, each composed of twobase plate, with a projecting active surface on one side of the same, aring of insulating material in contact with the same side of said plateand secured thereto, and surrounding the active surface, said base plateserving as the "support for the said insulating material, and a metalspacing washer 0r units on the sides thereof opposite from the activesurfaces.

48. A quenched spark-gap, composed of a plurality of units. eachcomposed of two similar halves, each of which has a metal base plate,with a projecting active surface on one side of the same, a ring ofinsulating material in contact with. the same side ,of said plate andsecured thereto, and surrounding the active surface and out of contactwith the same, said base plate serving as the support for the saidinsulating material, and a metal spacing washer or gasket compressedbetween such halves, in combination with a metal cooling plateassociated with the base plates of contiguous units on the sides thereofopposite from the active surfaces 49. A quenched spark-gap, composed ofa plurality of units, each composed 0f two similar halves, each of whichhas a metal base plate, with a projection on one side having an activesurface, a ring of insulating material in contact with the same sideonly of said plate and surrounding the active surface, and with theplane of the active surface extending to at least the plane of the ringof insulating material, and a metal spacing washer or gasket compressedbetween suclrhalves, in combination with a metal cooling plateassociated with the base plates of contiguous units on the sides thereofopposite from the active surfaces.

50. A quenched spark-gap, composed of a plurality of units, eachcomposed of two similar halves. each of which has a metal base plate.with a projection on one side having an active surface, a ring ofinsulating material in contact with the same side only of said plate,and surrounding the active surface; and out of contact therewith, andwith the plane of the active surface extending to at least the plane ofthe ring of insulating material, and a metal spacing washer or gasketcompressed between such halves, in combination with a metal coolingplate associated with the base plates of contiguous units on the sidesthereof opposite'from the active surfaces.

51. A quenched spark-gap, composed of a plurality of units, eachcomposed of two similar halves. each of which has a metal base plate,with a projection on one side having an active surface, a ring ofinsulating material in contact with the same side only of said plate andsecured thereto, and surrounding the active surface, and with the planeof the active surface extending to at least the plane of the ring ofinsulating material, and a metal spacing washer or gasket compressedbetween such halves, in

combination with a metal cooling plate asst)- ciated with the baseplates of contiguous;

units on the sides thereof opposite from the active surfaces.

52. A quenched spark-gap, composed of a plurality of units, eachcomposed of two similar halves, each of which has a metal base plate,with a projection on one side having an active surface, a ringpfinsulating material in contact with the same side only of said plate andsecured thereto, and surrounding the active surfaceand out of contactwith the same, and with the laneof the active surface extending to ateast the plane of the ring of insulating material, and a metal spacingwasher or gasket compressed between such halves, in combination with ametal cooling plate associated with the base plates of contiguous unitson the sides thereof opposite from the active surfaces.

A quenched spark gap, composed of a plurality of units, each composed oftwo similar halves, each of which has a metal base plate, with aprojecting active surface on one side of the same, a ring of insulatingmaterial in contact with the same side of said plate and surrounding theactive surface, and a metal ring on the side of the insulat'ing ringopposite from the base plate, and out of contact with the activesurface, and a metal spacing washer or gasket compressed between suchhalves, in combination with a metal cooling plate associated with thebase plates of contiguous units on the sides thereof opposite from theactive sur faces. v

54. A quenched spark gap, composed of a plurality of units, eachcomposed of two similar halves, each of which has a metal base plate,with a projecting active surface on one side of the same, a ring ofinsulating material in contact with the'same side of said plate andsurrounding the active sur-' face and out of contact therewith, and ametal ring on the side of the insulating ring opposite from the baseplate and out of contact with the activesurface, and a metal spacingwasher or gasket compressed between such halves, in combination with ametal cooling plate associated with the base plates of contiguous unitson the sides thereof opposite from the active surfaces.

55. A quenched spark gap composed of a plurality of units, each composedof two similar halves, each of which has'ametal base plate with aprojecting active surface on one side of the same,a ring of insulatingmaterial in contact with the same side of said plate and securedthereto, and surrounding the active surface, and a metal ring on theside of the insulating ring opposite from the base plate, and out ofcontact 'with the active surface, and a metal spacing washer or gasketcompressed between such halves, in combination with a metal coolingplate associated with'the base plates of contiguous units on the sidesthereof opposite from the active surfaces.-

50. A quenched spark gap composed of a plurality of units, each composedof two similar halves, each of which has a metal base plate with aprojecting active surface on one side of same, a ring of insulatin"material in contact with the same side 0? said base late and securedthereto, and surrounding the active surface, and out of contacttherewith, and a metal ring on the side of the insulating ring oppositefrom the ated with the base plates of contiguous units on the sidesthereo surfaces.

This specification si 'ncd and witnessed this 29th day of Deceniiier,1913.

RICHARD PFUND.

opposite from the active Witnesses:

J. F. COLEMAN, ANNA E. RnN'roN.

Copiea of this patent may be obtained for five cents each, by addressingthe Commissioner 0! Patents, Washington, D. 0.

